A standard high-frequency spindle has a shaft, a release unit, and a chuck that can be moved between a holding position and a freeing position. The chuck further has at least one retaining element that can be moved radially relative to the longitudinal axis of the spindle by changing the axial position of a spring-loaded actuating rod and that is provided to axially secure the position of a tool or a tool holder associated with the high-frequency spindle by positive engagement and radial frictional engagement.
High-frequency spindles are characterized by their high rotation speeds of greater than or equal to 50,000 rpm. There are already various known methods for changing or gripping tools or tool holders. A differentiation is made between a manual and an automatic gripping system. In the manual system, changing the tool and gripping the tool are effected by hand. In automatic gripping systems, gripping the tool is effected by means of a spring and replaceable collet chucks, such as, for example, disclosed in DE 199 20 264.
The use of collet chucks, however, can result in axial displacement of the tool along the longitudinal axis of the spindle during operation, and this produces inconsistencies in machining the workpiece. In addition, high-frequency spindles having an automatic gripping system with collet chucks have the problem that changing a tool involves changing the collet chucks, and the result is a considerable cost in terms of time. Necessitated by design, automatic gripping systems that are based on a shank cone or a hollow shank cone require a relatively large spindle diameter. A further problem is releasing the holding position in an automatic gripping system. Here force is often applied by a stationary release piston against the spindle bearing. Particularly in the case of high-frequency spindles, this axial force has negative effects on the service life of the spindle bearing.